Sweden joins talks to extend X-31 demonstrator project

US, GERMAN AND Swedish Government and industry officials met at ILA to discuss a follow-on to the German/US X-31 Enhanced Fighter Manoeuvrability technology-demonstration project.

US Navy X-31 programme manager Charles Johnson says that the discussions focused on a programme called the ADVENT, which will investigate advanced air-data systems for post-stall flight, extremely short take-off and landing (ESTOL), the use of a General Electric axisymmetric-vectoring engine nozzle (AVEN), and further research into tailless flight. Programme officials say that the surviving Rockwell/Daimler-Benz Aero- space (DASA) X-31A test aircraft has half its useful life left, and offers potential for further research.

The would-be partners hoped to agree how much funding each could contribute to the programme. Germany wants to incorporate thrust-vectoring technology to upgrades of the Eurofighter EF2000, while Sweden hopes to do the same for the Saab JAS39 Gripen. US Navy officials say that their interest focuses on upgrading McDonnell Douglas (MDC) F-18s, as well as US Air Force MDC F-15s and Lockheed Martin F-16s.

According to Hannes Ross, heading the programme at German industrial partner DASA, the advanced air-data research will concentrate on developing a system which can function well in the post-stall regime, without the need for the X-31's large noseboom.

The ESTOL investigations centre on the potential for operating thrust-vectoring aircraft from short or battle-damaged runways, and from aircraft carriers, says Johnson. Thrust vectoring could allow aircraft taking off to rotate early, while approaches could be made at high angles of attack - up to 70° - and low speed, levelling the aircraft off just before touchdown. According to Johnson, this could eliminate the need for arrester gear and offer "...substantial bring-back capability in weight and weapons".

The partners hope to fit the aircraft with a version of the AVEN engine nozzle, adapted to the X-31's GE F404 engine, and to investigate 100% tailless flight. The AVEN was flight-tested in 1994 on GE's larger F110, under the F-16 multi-axis thrust-vectoring programme.